1. Field of the invention
This invention relates to integrated circuit MOS FET devices and more particularly to diffusion barriers for forming improved metallization interfaces on the surface of silicon containing materials including gate electrodes and source/drain regions in a MOSFET device.
2. Description of Related Art
As CMOS technology is scaled down to the deep-submicrometer scale for ULSI, use is made of a Ti-salicide layer formed by a two-step annealing process which has been shown as an excellent metal silicide to reduce sheet resistance in source/drain regions. See S. P. Muraka, "Refractory silicides for integrated circuits," J. Vac. Sci Tech., vol. 17, pp. 775, (1980); C. K. Lau, Y. C. See, D. P. Scott, J. M. Bridges, S. A Perna, and R. D. Davies, "Titanium disilicide self-aligned source/drain+gate technology," in IEDM Tech. Dig. (1982) p. 714; T. Okamoto, K. Tsukamoto, M. Shimizu. and T. Matsukawa, "Titanium silicidation by halogen lamp annealing," J. Appl. Phys., vol. 57, p. 5251, (1985); and Michael E. Alperin, Thomas C. Hollaway, Roger A. Haken, Clayton D. Gosmeyer, Robert V. Kamaugh, and Walter D. Parmantle, "Development of the self-aligned Titanium silicide process for VLSI applications," IEEE J. Solid-State Circuits. vol. 20, no. 1, p. 61, (1985.)
Also TiN is an effective diffusion barrier metal to prevent TiSi.sub.2 morphology from agglomerating, and to retard junction spiking i.e., the aluminum (Al) in the contact hole interdiffuses into the Si-substrate during post thermal cycles. See M. Wittmer, "TiN and TaN as diffusion barriers in metallizations to silicon semiconductor devices," Appl. Phys. Lett., vol. 36, p. 456, (1980); C. Y. Ting and M. Wittmer, "Investigation of the Al/TiSi-2/Si contact system," J. Appl. Phys., vol. 54, p. 937, (1983); and S. W. Sun, J. J. Lee, B. Boeck, and R. L. Hance, "Al/W/TiN.sub.x /TiSiy/Si barrier technology for 1.0 .mu.m contacts," IEEE Electron Device Lett. vol. 9, p. 71, (1988).
In the past, many technologies to form self-aligned TiN/TiSi.sub.2 structures have been reported. See Hiroko Kaneko, Mitsumasa Koyanagi, Shinji Shimizu, Yukiko Kubota, and Seigo Kishino, "Novel submicrometer MOS devices by self-aligned nitridation of silicide," IEEE Trans. Electron Devices, vol. 33. no. 11. p. 1702 (1986); Y. H. Ku, E. Luis, D. K. Shih, S. K. Lee. D. L. Kwong, and N. 8. Alvi, "Stable, self-aligned TN.sub.x O.sub.y /TiSi.sub.2 contact formation for submicron device applications," Appl. Phys. Lett., vol. 50, no. 22. p. 1598, (1987); M. F. C. Willemsen, A. E. T. Kuiper, A. H. Reader. R. Hokke. and J. C. Barbour, "In situ investigation of TiN formation on top of TiSi.sub.2,- J. Vac. Sci. Tech., vol. B6, no. 1, p. 53, (1988); Avid Kamgar, F. A. Baiocchi. A- B. Emerson, T. T. Sheng, M. 1. Vasile, and Richard W. Haynes. "Self-aligned TiN barrier formation by rapid thermal nitridation of TiSi.sub.2 in ammonia." J. Appl. Phys., vol. 66. no. 6., p. 2395 (1989). However, the only one film formed by naked TiSi.sub.2 nitrided at high temperature in these technologies showed poor uniformity.
Recently, a thermally stable, uniform TiN formation process using N.sup.+ implantation was reported by A. Nishiyama, Y. Akasaka, Y. Ushiku. K. Hishioka, Y. Suizu, and M. Shiozaki, "A thermally stable salicide process using N.sub.2 implantation into TiSi.sub.2," in IEEE VMIC Conference, p. 310, (1990). But the leakage current of an n.sup.+ /p junction diode employed in this process was one order larger than that of diode without N.sup.+ implantation.
U.S. Pat. No. 5,397,744 of Sumi shows the use of N.sub.2 ion implanted into TiN to form an alpha Ti in a different type of a process.